3-Acetyl-4-hydroxyquinolin-2(1H)-one: resonance-assisted O—H...O hydrogen bonding

The molecule of the title compound, C11H9NO3, a pharmacologically important quinoline derivative, adopts an overall planar shape. The structure is stabilized by an intra­molecular O—H⋯O=C hydrogen bond, forming an S(6) hydrogen-bonded ring pattern. The O—H⋯O inter­action results in delocalization of the electron density within the dihydro­pyridine ring, as observed for resonance-assisted hydrogen bonds, leading to lengthening of the carbonyl O=C and pyridyl C=C bonds, and shortening of the C—OH bond in this hydrogen-bonded S(6) ring structure. The cooperative inter­molecular N—H⋯O hydrogen bonds cluster mol­ecules into closed dimers, characterized by an R22(8) ring pattern. Aromatic–aromatic stacking inter­actions are also observed in the packing, with an inter­planar distance of 3.352 Å and a slippage of 1.855 Å